UCL scientists have shown that there are widespread differences in how genes,
the basic building blocks of the human body, are expressed in men and women’s
brains.

Based on post-mortem adult human brain and spinal cord samples from over
100 individuals, scientists at the UCL Institute of Neurology were able to
study the expression of every gene in 12 brain regions. The results are
published today in Nature Communications.

They found that the way that the genes are expressed in the brains of
men and women were different in all major brain regions and these differences
involved 2.5% of all the genes expressed in the brain.

Among the many results, the researchers specifically looked at the gene
NRXN3, which has been implicated in autism. The gene is transcribed into two major
forms and the study results show that although one form is expressed similarly
in both men and women, the other is produced at lower levels in women in the
area of the brain called the thalamus. This observation could be important in
understanding the higher incidence of autism in males.

Our study provides the most complete information so far on how the sexes differ in terms of how their genes are expressed in the brain.

Dr Mina Ryten

Overall, the study suggests that there is a sex-bias in the way that
genes are expressed and regulated, leading to different functionality and
differences in susceptibility to brain diseases observed by neurologists and psychiatrists.

Dr. Mina Ryten, UCL Institute of Neurology and senior author of the
paper, said: “There is strong evidence to show that men and women differ in terms
of their susceptibility to neurological diseases, but up until now the basis of
that difference has been unclear.

“Our study provides the most complete information so far on how the
sexes differ in terms of how their genes are expressed in the brain. We have released our data so that others can
assess how any gene they are interested in is expressed differently between men
and women.”